1. Field of the Invention
The invention concerns a compression plate for a mammography device of the type wherein the plate has four sides and a base, with a bracket attached to the a first of the sides. The invention additionally concerns an x-ray diagnostic device with such a compression plate.
2. Description of the Prior Art
A mammography device basically includes a stand with an arm that carries an x-ray tube and a subject table as well as a compression plate of the above type arranged between the x-ray tube and the subject table. The plate is connected by the bracket to the arm and can be moved along the arm. In such devices, the arm is rotatably connected to the stand by a connector. A mammography device of this type is described in the specification sheet of the company Bennet Trex Medical with the title “The MF-150 Mammography System”. Furthermore, a larger number of compression plates are shown therein for selection, which can be mounted on the mammography device. These compression plates are, like most plates, provided with a metal frame. The metal frame that is attached to the bracket runs along the side to which the bracket is attached and along at least one part of another side that joins the aforementioned side. The metal frame is provided to stabilize the compression plate. The two sides are arranged lateral to the base of the compression plate.
Smaller compression plates are used in the examination of relatively small breasts, and when the breasts are of normal size or are larger than normal, the x-ray technician changes to one of the larger compression plates. This ensues primarily so that the x-ray technician can center, on the subject table, the breast to be compressed, such that the center ray of the x-ray beam intersects the hypothetical central axis of the breast. In the x-ray exposure obtained such an examination, the divergent x-ray field is less, which results in a clearer and sharper image of the subject.
A further advantage is that, with a compression plate adapted to a breast size, the x-ray technician can easily reach the breast in order to correct, among other things, possible skin folds on the breast before the compression thereof. A disadvantage with breast-adapted compression plates exists in particular in a horizontal exposure, when the technician wants to image organs and tissues above the compressed breast. With a breast-adapted compression plate, it often occurs in such an exposure that the x-ray field also includes the metal frame of the plate, which results an unacceptable x-ray image. A further disadvantage is that an exchange of compression plates dependent on the breast size is time-consuming for the x-ray technician. Additionally, it is relatively expensive to acquire a larger number of compression plates for each mammography device.